The invention relates to a mask for corpuscular electron lithography.
The exposure times are very long given employment of an electron projector for generating structures on a semiconductor wafer, and the costs are therefore very high. An economical employment of the electron projector for the mass production of structures on, for example, semiconductors (integrated circuits) was therefore previously impossible.
The employment of the electron projector for generating structures is known, for example, from the publication by R. Ward in "Electronics", Nov. 3, 1981, 144 ff, or from European patent application EP0074691 A or from U.S. Pat. No. 3,585,433 incorporated herein by reference. Given this known method, the mask standard in lithographic methods for generating structures is additionally coated with cesium iodide so that, given irradiation of the mask with light, photoelectrons are emitted in the transparent regions of the mask. These photoelectrons in turn are imaged on the semiconductor wafer by means of parallel electrical and magnetic fields on the semiconductor wafer coated with photosensitive resist for generating structures. The exposure time is given by the quotient of the resist sensitivity of the photosensitive resist applied to the semiconductor wafer and of the cathode current density of the photocathode situated on the mask. This exposure time is on the order of 100 s given, for example, a 10.sup.-7 A/cm.sup.2 cathode current density of the photocathode situated on the mask and given a standard resist sensitivity of the photosensitive resist disposed on the semiconductor wafer.